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Lowering the temperatures in heating systems is the key to decarbonizing the heat supply in the building sector, because it is a door opener to greater integration of renewable heat, the use of excess heat and to improve compatibility for heat pumps. This often fails because heating systems, especially in unrenovated building stock, usually require high supply temperatures. Previous studies on temperature reduction in existing buildings are performed mainly numerically, whereas in this research the numeric calculations are validated by measurements. For this purpose, a demonstrator with two different ceiling heating systems is integrated in the listed architecture building of the Technical University of Darmstadt and the achievable temperature reduction is investigated. Based on this, parameter variations are conducted through a simulation model in order to test the feasibility of the concept for the entire building. The results show that even with an unrenovated building envelope, a significant temperature reduction to below 45 °C is possible without exceeding the normative limits of thermal comfort. With moderate building envelope renovation, the reduction is possible even to below 36 °C. The measures investigated can make the building compatible with renewable heat potentials without negative impacts on the cultural heritage.

Розглянуто комбіновану теплонасосно-рекуператорну схему водяного опалення і вентиляції з використанням теплоти ґрунту та вентиляційних викидів. Виконано термодинамічний аналіз схеми теплопостачання, на основі якого визначені температурні параметри у вузлових точках системи, питомі затрати зовнішньої енергії на одиницю виробленої теплоти на вході в об’єкт опалення та вентиляції та частку теплового навантаження, що покривається ґрунтовим теплообмінником. Побудовано та проаналізовано графічні залежності критеріїв ефективності від величин, що визначають умови роботи схеми. Проведено співставлення отриманих критеріїв енергоефективності з відповідними значеннями для традиційної теплонасосної системи з ґрунтовим теплообмінником., The combined heat pump-recuperative scheme of water heating and ventilation using ground heat and ventilation emissions is considered. A thermodynamic analysis of the heat supply scheme was completed. Based on this analysis, the temperature parameters at the nodal points of the system, the unit cost of external energy per unit of heat produced at the entrance to the object of heating and ventilation and the proportion of heat load covered by the soil heat exchanger are determined. The graphical dependences of the efficiency criteria on the quantities that determine the conditions of operation of the circuit are constructed and analysed. A comparison of the obtained energy efficiency criteria with the corresponding values for a traditional heat pump system with the ground heat exchanger was completed. The introduction of the proposed combined scheme increases the air temperature supplied to the heater of the ventilation system. This, in turn, reduces the capacity of the heat exchangers of the ventilation system and improves the conditions of their operation, reducing the risk of icing over ducts. The proposed heat pump scheme leads to a decrease in specific energy consumption per unit of heat to meet the needs of water heating and ventilation of the premises. The energy efficiency of the heat supply system increases with the increase of both the recuperation coefficient of the recuperator and the relative heat consumption for ventilation compared with the heat consumption for heating. Reducing the total energy consumption for the heating and ventilation system results not only in increasing the energy efficiency of the heat supply system, but also leads to a decrease in capital costs for the construction of a heat pump unit (in particular, for the construction of a pre-heavily ground heat exchanger) in proportion to the reduction of its required capacity.

When buildings become more energy effective, the temperature levels of district heating systems need to be lower to decrease the losses from the distribution system and to keep district heating a competitive alternative on the heating market. For this reason, buildings that are refurbished need to be adapted to suit low-temperature district heating. The aim of this paper is to examine whether four different energy refurbishment packages (ERPs) can be used for lowering the temperature need of a multi-family buildings space heating and domestic hot water (DHW) system as well as to analyse the impact of the DHW circulation system on the return temperature. The results show that for all ERPs examined in this study, the space heating supply temperature agreed well with the temperature levels of a low-temperature district heating system. The results show that the temperature need of the DHW system will determine the supply temperature of the district heating system. In addition, the amount of days with heating demand decreases for all ERPs, which further increases the influence of the DHW system on the district heating system. In conclusion, the DHW system needs to be improved to enable the temperature levels of a low-temperature district heating system. Funding Agencies|industrial post-graduate school Reesbe; Knowledge Foundation (KK-stiftelsen); AB Borlange Energi; AB Stora Tunabyggen

Renewable energy sources for the purpose of heating buildings cooperate perfectly with so-called low-temperature heating systems. Water loop surface heating systems had been thoroughly tested. In contrast, thermal performance of wall panels with heat pipes have not been fully recognized, yet. The determination of the thermal power as well as the control of panels thermal performance cannot be performed with the methods developed for water loop systems. In this paper, the novel heating panels with heat pipes were tested to analyze the possibility of controlling their performance by changing the mass flowrate of heating water and its temperature. Specific heating power of the investigated panels varies from 16.9 W/m2 to 93.8 W/m2 when supplying a water temperature ranging from 35 °C to 65 °C and mass flowrate from 10 g/s to 47.5 g/s. Investigations revealed that the thermal performance of the panels is more sensitive to the changes of temperature than to the changes of mass flowrate of supplying water, and thus, should be controlled by changing the supply water temperature at low mass flowrates to obtain a low energy usage of pumps (diminished pressure losses) and good quality of controlling.

As existing buildings are renovated and energy-efficiency measures are implemented to meet requirements for reduced energy consumption, it becomes easier to heat our homes with low-temperature heating. This study set out to investigate how much the heating system supply temperature can be reduced in typical Danish single-family houses constructed in the 1900s. The study provides a simplified theoretical overview of typical building constructions and standards for the calculation of design heat loss and design heating power in Denmark in the 1900s. The heating power and heating demand in six typical Danish single-family houses constructed in the 1900s were estimated based on simple steady-state calculations. We found that the radiators in existing single-family houses should not necessarilrbe expected to be over-dimensioned compared to current design heat loss. However, there is considerable potential for using low-temperature space heating in existing single-family houses in typical operation conditions. Older houses were not always found to require higher heating system temperatures than newer houses. We found that when these houses have gone through reasonable energy renovations, most of them can be heated with a supply temperature below 50 degrees C for more than 97% of the year. (C) 2016 Elsevier B.V. All rights reserved.

Low-temperature heating provides an efficient way of heating our buildings. To obtain a high efficiency it is important that the heating systems in the buildings are operated with both low supply and return temperatures. This study set out to investigate how typical assumptions in the modelling of heat emissions from existing hydraulic radiators affects the heating system return temperatures calculated in a building simulation model. An existing single family house with hydraulic radiators was modelled in the simulation program IDA-ICE. Simulations were performed with various levels of detail and the calculated indoor temperatures and radiator return temperatures were compared to temperatures measured in the case house. The results showed that the detail of the simulation model has a large influence on the results obtained. The estimated return temperatures from the radiators varied by up to 16 degrees C depending on the assumptions made in the simulation model. The results indicated that a detailed building simulation model can provide a good estimate of the actual heating system operation, provided that actual radiators and realistic indoor temperatures are taken into account in the model. (C) 2016 Elsevier B.V. All rights reserved.

The high energy use in the European building stock is attributable to the large share of old buildings with poor energy performance. Energy renovation of buildings is therefore vital in the work towards energy efficiency and reduced environmental impact in the EU. Yet, the strategies and energy system implications of this work have not been made clear, and the rate of building renovation is currently very low. The aim of this thesis is to investigate the economic and environmental aspects of energy renovation strategies, with two main objectives: Renovation of Swedish district heated multi-family houses, including life-cycle cost and environmental analysis and impact on the local energy system; Renovation of European residential and office buildings, including life-cycle cost and environmental analysis and influence of climatic conditions. Buildings typical for the respective regions and the period of construction 1945-1970 were simulated, in order to determine the feasibility and energy saving potential of energy renovation measures in European climates. A variety of systems for heating, cooling and ventilation were studied, as well as solar energy systems, with focus on heat pumps, district heating, low-temperature heating systems and air heat recovery. Compared to normal building renovation, energy renovation can often reduce the life-cycle costs and environmental impact. In renovation of typical European office buildings, as well as Southern European multi-family houses, more ambitious renovation levels can also be more profitable. Exhaust air heat pumps can be cost-effective complements in district heated multi-family houses, while ventilation with heat recovery is more expensive but also more likely to reduce the primary energy use. From a system perspective, simple exhaust ventilation can reduce the primary energy use in the district-heating plant as much as an exhaust air heat pump, due to the lower electricity use. Byggnadssektorn står för omkring 40 % av den totala energianvändningen i EU. Den höga energianvändningen i Europeiska byggnader kan till stor del tillskrivas den stora andelen gamla byggnader med dålig energiprestanda. Energirenovering av byggnader, eller energieffektivisering genom renovering, kan därför anses utgöra en central del i arbetet mot EU:s klimat- och energimål för år 2030. Trots detta är det ännu inte helt klarlagt vilka strategier som ska tillämpas för att uppnå detta och hur det påverkar energisystemet, och i nuläget är renoveringstakten fortfarande väldigt låg. Målet med denna avhandling är att undersöka ekonomiska och miljömässiga aspekter av strategier för energirenovering, såväl byggnadsskalsåtgärder som aktiva system, för typiska bostads- och kontorsbyggnader i Sverige och i andra Europeiska regioner. Mer specifikt har arbetet följande två inriktningar: Renovering av svenska, fjärrvärmevärmda flerfamiljshus, inklusive livscykelkostnadsanalys och livscykelmiljöanalys samt påverkan på det lokala energisystemet; Renovering av Europeiska bostads- och kontorsbyggnader, inklusive livscykelkostnadsanalys och livscykelmiljöanalys samt påverkan av klimatförutsättningar. Byggnader typiska för respektive region och byggnadsperioden 1945-1970 modellerades och användes i simuleringar för att fastställa den övergripande möjligheten och energibesparingspotentialen för olika renoveringsåtgärder i Europeiska klimat. En rad system för värme, kyla och ventilation studeras, samt solenergisystem, med fokus på värmepumpar, fjärrvärme, lågtemperaturvärmesystem och värmeåtervinning ur frånluft. Jämfört med renovering av byggnader utan energieffektiviseringsåtgärder kan energirenovering i många fall minska såväl livscykelkostnaden som miljöpåverkan. Vid renovering av typiska Europeiska kontorsbyggnader lönar det sig mer att renovera ner till ett uppvärmningsbehov på 25 kWh/(m²∙år) än 45 kWh/(m²∙år), då den minskade kostnaden för köpt energi väger upp den ökade kostnaden för isolering. För flerfamiljshus i södra Europa kan mer ambitiösa mål gällande värmebehov också vara lönsamma, medan en mer måttlig nivå är lämplig för småhus. Solvärme- eller solelsystem kan användas för att minska byggnaders miljöpåverkan. Utan subventioner eller inmatningstariff för överskottsel kan det bli svårt att få lönsamhet i dessa system för kontorsbyggnader i Nord- och Centraleuropa samt för småhus. För flerfamiljshus kan solenergisystem dock sänka den totala livscykelkostnaden, såväl i södra som i norra Europa. Värmeåtervinning och lågtemperaturvärmesystem visade sig båda ha större inverkan i kallare klimat. Lågtemperaturvärmesystem förbättrar värmefaktorn för värmepumpar, i synnerhet när uppvärmningsbehovet är stort i förhållande till varmvattenbehovet. Vid renovering av byggnader med vattenburna radiatorer kan konvertering till tilluftsradiatorer sänka framledningstemperaturen i värmesystemet. I svenska flerfamiljshus kan frånluftsvärmepump vara ett kostnadseffektivt komplement till fjärrvärme, medan från- och tilluftsventilation med värmeåtervinning är dyrare men mer sannolikt att ge en minskad primärenergianvändning. I ett systemperspektiv kan frånluftsventilation utan värmeåtervinning minska primärenergianvändningen i fjärrvärmeverket lika mycket som en frånluftsvärmepump, tack vare den lägre elanvändningen. QC 20170509 iNSPiRe

Renovation of existing buildings is important in the work towards increased energy efficiency and reduced environmental impact. The present paper treats energy renovation measures for a Swedish district heated multi-family house, evaluated through dynamic simulation. Insulation of roof and façade, better insulating windows and flow-reducing water taps, in combination with different HVAC systems for recovery of heat from exhaust air, were assessed in terms of life cycle cost, discounted payback period, primary energy consumption, CO₂ emissions and non-renewable energy consumption. The HVAC systems were based on the existing district heating substation and included mechanical ventilation with heat recovery and different configurations of exhaust air heat pump. Compared to a renovation without energy saving measures, the combination of new windows, insulation, flow-reducing taps and an exhaust air a heat pump gave up to 24% lower life cycle cost. Adding insulation on roof and façade, the primary energy consumption was reduced by up to 58%, CO₂ emissions up to 65% and non-renewable energy consumption up to 56%. Ventilation with heat recovery also reduced the environmental impact but was not economically profitable in the studied cases. With a margin perspective on electricity consumption, the environmental impact of installing heat pumps or air heat recovery in district heated houses is increased. Low-temperature heating improved the seasonal performance factor of the heat pump by up to 11% and reduced the environmental impact. QC 20160809

Панферов Владимир Иванович, д-р техн. наук, профессор, зав. кафедрой теплогазоснабжения и вентиляции, Южно-Уральский государственный университет, г. Челябинск; tgsiv@mail.ru. Панферов Сергей Владимирович, канд. техн. наук, доцент кафедры теплогазоснабжения и вентиляции, Южно-Уральский государственный университет, г. Челябинск; tgsiv@mail.ru. V.I. Panferov, S.V. Panferov tgsiv@mail.ru South Ural State University, Chelyabinsk, Russian Federation The problem of flow control of the heat carrier with a significant reduction of its temperature is studied. Several solutions to this problem are found taking into account the required amount of heat to the consumer. In this case, the heating supply object seems to be an equivalent heating device. An acceptable range of temperature reduction in the heat supply pipe is found in which the problem of 100 % heat supply can be solved by increasing the flow of the heat carrier. It has been shown that this range can be significantly extended if there can be some decline in the quality of the heating supply – delivered volume of heat. The results can be used in the development of low-temperature heating modes – graphs of quantitative regulation of the heating supply. Рассмотрена задача управления расходом теплоносителя при существенном снижении его температуры. Разработано несколько вариантов решения этой задачи, в том числе и при условии съема потребителем требуемого по погоде количества теплоты. При этом, как это и общепринято, объект теплоснабжения представляется эквивалентным отопительным прибором. Найден допустимый диапазон снижения температуры в подающем теплопроводе, при котором задача 100%-ного теплоснабжения еще может быть решена за счет увеличения расхода теплоносителя. Показано, что этот диапазон может быть заметно расширен, если допускается некоторое ухудшение качества теплоснабжения – количества доставляемой теплоты. Результаты работы могут быть использованы при разработке режимов низкотемпературного теплоснабжения – графиков количественного регулирования отпуска теплоты (тепловой нагрузки).

As an energy-efficient alternative in cold climate countries such as Sweden, low-temperature heating (LTH) technology has shown promising advantages and shortcuts to contribute to the efficiency of heat supply, as well as to the overall sustainability of building performance. The goal of this thesis is to contribute to the development of methodologies and modeling tools to support sustainable retrofitting in the Swedish housing stock. A combination of three integrated modeling techniques was developed. The main focus of this work was implementing LTH in retrofitting practice. The principle of the developed methods can be regarded as a top-down approach, underpinning the general definition of LTH and sustainability criteria. It was found that a preliminary compilation and investigation of the building typology could simplify the retrofitting decision-making. Also, 36–54% of final energy savings could be achieved in studied housing archetypes by effective energy retrofitting. Combining LTH radiators with ventilation heat recovery showed the largest contributions. Below 30 W/m2 (12 W/ m3) heating demand, both radiators (ventilation radiators and baseboard radiator) could work as LTH. These reduced supply temperatures further improved the COP of air-source heat pumps by approximately 12% - 18%. For retrofitting of conventional radiators, there was no concrete evidence to support Type 22 having higher thermal efficiency than Type 21, for the Swedish climate and heating seasons. The achievements and full potential of implementing LTH in retrofitting were found to require not only efficient radiators, but also a well-designed package – insulation, piping, pumping and energy supply system - that suited the current heating demand of the building, given the local climate condition. However, it should also be highlighted that retrofitting incorporating all evaluated measures would not always yield higher long-term economic profits among different archetypes. It is important to find the trade-off between cost-effectiveness and energy savings in similar archetypes - instead of using a “one size fits all” types of solution. For conventional retrofit measures, such as insulations of building envelopes, it was necessary to evaluate the embodied energy during the whole retrofitting process. Den ökande relativa energianvändningen i bostadsbyggnader i stadsmiljö har lett till högre krav på energieffektivit och hållbar omvandling av redan existerande bostadsbyggnader. En viktig förutsättning för att genomföra en sådan omvandling är att först utveckla metoder för hur effektiva beslut om renovering ska ske, samt att utveckla teknik för hållbar renovering. Lågtemperatursuppvärmning (LTH) har visat sig ha fördelar som ett hållbart och energieffektivt alternativ i länder med kallt klimat som Sverige. Metoden bidra till ökad effektivitet för uppvärmning och minskade energibehov för byggnadskomplexet. Det saknas fortfarande flera steg för hur man ska utforma modelleringsverktyg och utveckla kostnadseffektiva metoder för beslutsfattning och implementering av LTH i redan existerande byggnader. Dessutom försvårar avsaknaden av dessa verktyg och metoder genomförandet av kritiska utvärderingar av renoveringsalternativ utifrån hållbarhets- och effektivitetssynpunkt med huvudfokus på energibesparingspotential, miljöpåverkan och nöjdhet hos de boende. Dessa frågor undersöks i denna avhandling i samband med renovering av existerande bostadsbyggnader i Sverige. Målet är att bidra till utvecklingen av metoder och modelleringsverktyg för hållbar renovering. Under arbetet utvecklades tre modelleringskoncept som integrerats med varandra och som svarar för olika steg i renoveringsmodelleringen. Huvudfokus i arbetet var att göra LTH till en del av vår renoveringspraxis. De renoveringsalternativ som studerats i arbetet inkluderar renovering av klimatskalet för att minska energibehovet samt implementering av LTH-radiatorer och där påvisa deras fördelar för valt primärenergisystem. Analysen omfattar även den sammantagna effekten av och de ömsesidiga beroenden som föreligger mellan olika renoveringsåtgärder. Här utvecklade metoder kan sägas följa en ”uppifrån och ner” strategi och stärker LTH som ett uppvärmningsalternativ som uppfyller hållbarhetskriterier. Avhandlingen visar att effektiv renovering av energisystem kan minska det slutliga energibehovet med 36-54 % i de studerade byggnadstyperna. Kombinationen av LTH-radiatorer med värmeåtervinning från ventilation gav de allra största positiva bidragen. LTH-radiatorerna (ventilationsradiatorer och värmelister) fungerade som lågtemperatursuppvärmning vid uppvärmningsbehov under 30 W/m2 (12 W/ m3) och som ultra-lågtemperaturuppvärmning vid uppvärmningsbehov under 10 W/m2 (4 W/ m3). De låga framledningstemperaturer som leds till LTH-radiatorer bidrar dessutom till att öka COP (värmefaktorn) för luftvärmepumpar med 12 – 18 %, jämfört med traditionella radiatorer med lika stor värmeavgivande area. Något konkret stöd fanns inte för att Typ 22-radiatorer (dubbel konvektionsplåt) skulle ha högre värmeeffektivitet än Typ 21-radiatorer (enkel konvektionsplåt) för svenska klimatetförhållanden. Ökat antal konvektorplåtar visade sig alltså inte nödvändigtvis leda till ökad värmeeffektivitet. Tröskelvärdet för när Typ 11-radiatorer (enkel panel) presterar sämre än den mest effektiva radiatortypen, Typ 21-radiatorer (dubbel panel) som även har bättre exergiprestanda, visade sig vara ett värmebehov av 480 W/rum. För att uppnå full potential för LTH-radiatorer som renoveringsalternativ visade det sig utöver mer effektiva radiatorer även behövas ett välutformat system av rör, pumpar och energitillförsel, anpassade till byggnadens värmebehov före renovering vid rådande klimat. Renovering som inkluderar alla möjliga alternativ leder inte alltid till högre långsiktig ekonomisk avkastning. Det är viktigt att finna en balans mellan kostnadseffektivitet och energibesparing för likande byggnadstyper, i stället för att utveckla en enda lösning som ska passa överallt. För traditionella renoveringsalternativ, så som isolering, var det nödvändigt att utvärdera den inbäddade energin under hela renoveringsprocessen. Stor risk för överskattad hållbarhet föreligger om man inte beaktar detta. QC 20160929 D6559

Herbal water is prepared as a by-product in the process of steam distillation of herbs. In this report, we considered a way to speed up the ripening of lavender, chamomile and rose water. These waters were heated at 30, 40 and 50 degrees and evaluated for a sensory test. Food sanitation inspections(Coliform bacteria, Staphylococcus aureus and Aerobic bacteria counts) were carried out on these waters. As a result, the best way to accelerate ripening is to heat at 30 degrees for 10 min in all the herbal waters. The results, however, showed the differences between each herb in the process of aging. When heated in lavender water bad odor decreased, in chamomile water aromatic odor increased, and in rose water bothe bad odor decreased and aromatic odor increased. These herbal waters were uncontaminated. These waters can be expected to be as used new food and cosmetic material.

The regularities of the corrosion of steel 45 after severe plastic deformation and subsequent low-temperature heating., Исследованы закономерности коррозии стали 45 после интенсивной пластической деформации и последующего низкотемпературного нагрева., Досліджено закономірності корозії сталі 45 після інтенсивної пластичної деформації та подальшого низькотемпературного нагріву.

Рассматривается проблема низкотемпературного теплоснабжения отапливаемых зданий. Показано, что существует оптимальная температура теплоносителя, при которой достигается минимум потерь теплоты в теплотранспортных системах. Это открывает новые подходы к постановке и решению задач проектирования тепловых сетей. We consider the problem of low temperature heat supply of heated buildings. It is shown that there is an optimal heat carrier temperature at which there is minimum loss of heat in the heat transport systems. This reveals new approaches to the formulation and the solution of problems of heat networks. Гавей Ольга Фёдоровна, инженер, Центр энергосберегающих технологий ОАО «ММК». Область научных интересов: энергосбережение в системах теплоснабжения и отопления. Тел.: 89124040412. Gavey Olga Fedorovna, engineer of the Center of Energy Efficient Technologies of Joint stock company “Magnitogorsk Iron and Steel Works”. Research interests: energy efficiency in the systems of heat supply and ventilation. Tel.: 89124040412. Панферов Владимир Иванович, доктор технических наук, профессор, заведующий кафедрой «Теплогазоснабжение и вентиляция», Южно-Уральский государственный университет. Область научных интересов: моделирование и оптимизация теплотехнических процессов и систем, автоматизация технологических объектов. Тел.: 8 (351)2679688. Panferov Vladimir Ivanovich, Dr.Sc. (Engineering), professor, head of the faculty “Heat and gas supply and ventilation”, South Ural State University. Research interests: modeling and optimization of heat engineering processes and systems, automation of technological objects. Tel.: 8 (351) 2679688.

Problems of simulation of electromagnetic field taking into account hysteresis effect, at low-temperature heating of ferromagnetic steel, are considered in the present paper. Methods of numerical calculation of induction, resistive, and inductionresistive systems for ferromagnetic steel heating are developed. Comparison of electromagnetic field parameters in ferromagnetic steel for induction, resistive, and induction-resistive heating units is made, based on the methods obtained. The hysteresis effect contribution into the total heat output in the heated ferromagnetic material is estimated.

The European Union has adopted a plan to decrease 20 % of total energy consumption through improved energy efficiency by 2020. One way of achieving this challenging goal may be to use efficient water-based heating systems supplied by heat pumps or othersustainable systems. The goal of this research was to analyze and improve the thermalperformance of water-based baseboard heaters at low-temperature water supply. Both numerical (CFD) and analytical simulations were used to investigate the heat efficiency of the system. An additional objective of this work was to ensure that the indoor thermal comfort was satisfied in spaces served by such a low-temperature heating system. Analyses showed that it was fully possible to cover both transmission and ventilation heatl osses using baseboard heaters supplied by 45 °C water flow. The conventional baseboards, however, showed problems in suppressing the cold air down-flow created by 2.0 m high glazing and an outdoor temperature of – 12 °C. The draught discomfort at ankle level was slightly above the upper limit recommended by international and national standards. On the other hand, thermal baseboards with integrated ventilation air supply showed better ability to neutralize cold downdraught at the same height and conditions. Calculations also showed that the heat output from the integrated system with one ventilation inlet was approximately twiceas high as that of the conventional one. The general conclusion from this work was that low-temperature baseboards, especially with integrated ventilation air supply, are an efficient heating system and able to be combined with devices that utilize the low-quality sustainable energy sources such as heat pumps. QC 20101029